The present invention pertains to light water reactor zirconium base alloy fuel claddings for application in pressurized water, boiling water and heavy water reactors. It is especially concerned with tubular fuel claddings composed of a single zirconium base material.
In the past, a number of nuclear fuel cladding designs have been proposed, each having the goal of minimizing PCI (pellet-cladding-interaction) crack propagation. These designs have all involved the placing of a comparatively soft material as a thin, inner layer on the inside surface of a conventional zirconium base alloy (e.g. Zircaloy 2 or 4) tube. The cost of the soft material, and the cost for its incorporation into the fuel cladding tube adds significantly to the final cost of the tubing. PCI resistant liner materials have typically had a fully recrystallized microstructure, and relatively low strength and poor aqueous corrosion resistance compared to the conventional cladding materials Zircaloy 2 and 4. These properties have made them unsuitable for use as a material which could form the entire cladding tube. There, therefore, exists a need for a fuel cladding design in which a single material forms the tube and provides a cladding which has a combination of excellent PCI crack propagation resistance, and excellent aqueous corrosion properties as well as good structural mechanical properties.